1. Field of the Invention
The present invention relates to a method for fabricating a thin film pattern, a device and fabricating method therefor, a method for fabricating a liquid crystal display, a liquid crystal display, a method for fabricating an active matrix substrate, an electro-optical apparatus, and an electrical apparatus.
Priority is claimed on Japanese Patent Application No. 2003-155858, filed May, 2003, Japanese Patent Application No. 2003-155865, filed May, 2003, Japanese Patent Application No. 2003-155866, filed May, 2003, Japanese Patent Application No. 2003-155867, filed May, 2003, Japanese Patent Application No. 2004-103418, filed March, 2004, the contents of which are incorporated herein by reference.
2. Description of Related Art
To fabricate a device having wiring used for electronic circuits or integrated circuits, a photolithographic method, for example, is used. This photolithographic method forms a wiring pattern on a thin film by applying a photosensitive material called a resist to a substrate that has had a conducting film applied thereto in advance, the circuit pattern is developed by being irradiated, and the conducting film is etched that conforms to the resist pattern. This photolithographic method requires large-scale equipment and complicated steps. In addition, the material use efficiency is only a few percent, most of the product must be discarded, and thus the fabrication cost is high.
In contrast, U.S. Pat. No. 5,132,248 proposes a method wherein a wiring pattern is formed on a substrate by using an ink ejection method in which a liquid material is ejected in a droplet form from a liquid discharge head, also known as an inkjet method. In this method, a wiring pattern ink, which is a function liquid having conductive particles such as gold particles dispersed therein, is applied directly to a substrate, and subsequently this ink is converted to a thin film conducting film pattern by heat treatment and laser irradiation. According to this method, there are the merits that photolithography becomes unnecessary, the process can be greatly simplified, and the amount of raw materials used becomes small.
At the same time, with the popularization of mobile devices such as mobile telephones, thin and light liquid crystal displays have become widely used. This type of liquid crystal display has a liquid crystal interposed between an upper substrate and a lower substrate.
An example of the lower substrate is shown in FIG. 48. As shown in this figure, the lower substrate 1 is formed by providing a glass substrate 2, a gate scanning line electrode and a source electrode 4 that are laid out so as to intersect each other on this glass substrate 1, a drain electrode 5 similarly laid out on the glass substrate 2, an image electrode (ITO) 6 connected to this drain electrode 5, an insulating layer 7 interposed between the gate scanning line electrode 3 and the source electrode 4, and a TFT (thin film transistor) consisting of a thin film semiconductor.
In the formation of each of the metal wires on the substrate 1, conventionally a method in which, for example, a dry process and photoetching are combined is used, but the dry process has the drawbacks that the fabrication cost is high and adapting it to increasingly larger substrate sizes is difficult. Thus, a method in which the metal wiring is formed on the glass substrate by using an inkjet method is being used (refer, for example, to Japanese Unexamined Patent Application, First Publication No. 2002-164635).
However, the conventional technology described above has the following problems.
Because the wiring patterns are formed by conductive particles applied to the surface of the substrate, the films that consist of the conductive particles protrude from the substrate surface, and this is a cause of obstructing the thin formation of the device.
In addition, there is a concern this may hinder the increasing integration even for devices having a wiring pattern formed over several layers on the substrate.
In addition, in other methods as well, as shown in FIG. 48, many irregularities remain on the surface of the completed product. If these irregularities become comparatively large, there is a concern that display distortions will occur when the liquid crystal display is assembled.
Specifically, a rubbing treatment will be carried out on the upper surface of this lower substrate 1 after formation of the orientation film. However, there is a concern that differences will occur in the results of the rubbing at the concave and convex parts. When such unevenness in the rubbing treatment occurs, differences in the orientation force of the liquid crystal will occur between parts thereof, and display distortions occur as a result.
In consideration of the problems described above, objects of the present invention are to provide method for fabricating a thin film pattern that can realize increased thinness, a device and fabricating method for the same, an electro-optical apparatus, and electrical apparatus.